Method of making a body member conformable disposable articles

ABSTRACT

Body member conformable disposable articles and processes for their preparation are described. A preferred embodiment is a disposable absorbent article comprising a flexible, elastic, moisture impermeable backing film, an absorbent layer superposed thereon and a moisture permeable topsheet joined to the backing film along the edges of the topsheet. A portion of at least one longitudinal edge of the backing film has been folded upon itself and heat sealed together at the fold so that when the backing film is laid flat the aforementioned longitudinal edge will be in stretched condition, thus conferring body member conformability to the article.

This is a continuation of application Ser. No. 926,601, filed Nov. 3,1986, now abandoned, which is a division of Ser. No. 838,440, filed Mar.10 1986, now U.S. Pat. No. 4,662,874.

The present invention relates to body member conformable disposablearticles, especially disposable absorbent articles such as diapers andincontinence pads, and processes for their preparation.

BACKGROUND OF THE INVENTION

In recent years the demand for disposable absorbent articles, such asdisposable diapers has been increasing. It is important that thesediapers should achieve conformability to a body member. Disposablediapers generally are provided with a liquid impermeable backing film,an absorbent layer superposed on the backing film and a liquid permeabletopsheet. Diapers are normally fitted to the wearer from a flat state asa result of which they are not completely effective since gaps maydevelop in the area around the legs through which fluid leaks. In orderto overcome this disadvantage, many diapers are now provided withelastic leg stretch components. These stretch components normallycomprise elastic bands which are applied to the backing film of thediaper using a hot melt adhesive. The elastic bands are normally appliedto the film under stretch and as soon as the hot melt adhesive cools andsolidifies, the elastic band relaxes to the original shape, thus pullingthe film with it and corrugating the film. This method is expensive andrequires a great deal of care to obtain an efficient and proper stretch.Other prior art attempts to overcome the problem of leakage includeproviding an absorbent layer with an hourglass-like shape or sealing anelastic band between the backing film and the topsheet along thelongitudinal edge while in stretch condition for some conformance aroundthe legs. The former approach is accompanied by a reduction in theamount of absorbent material in a critical area and further does notcompletely avoid gap formation. The latter approach, although decreasinggap formation, has tended to produce a less comfortable productespecially if the wearer is an infant. The sealing of an elastic band tothe topsheet and backing film may be carried out by the application ofadhesive to the band or to both backing film and topsheet. This methodof anchoring the rubber band is a cumbersome procedure and moreovertends to produce a harsh feeling on the surface contacting the wearer'sskin.

Applicant's copending application Ser. No. 286,441 filed July 24, 1981,now abandoned, overcomes the latter disadvantage in that it consists ofapplying an elastic pressure-sensitive adhesive tape on the outside ofthe backing film so that there is no adverse feeling on the surfacecontacting the wearer's skin.

Prior art disposable diapers have also suffered from the disadvantage ofbeing somewhat unyielding and paper-like and incapable of stretching toany extent, i.e., they lacked elasticity and conformability to the bodymembers to which they are applied. U.S. Pat. No. 4,166,464 overcomes theproblem of conformability to the body members, by disclosing a diaperhaving a thin flexible elastic and easily stretchable thermoplasticbacking film as well as a liquid permeable topsheet which is extensibleor stretchable such as certain nonwoven fabrics. However, even thoughthe backing film is elastic, that portion of the edge of the backingfilm adapted to be wrapped around a body member does not necessarilyconform completely to the shape of the body member so that a certainamount of leakage of fluid may still occur. This problem is overcome inaccordance with the present invention, by providing an elastic backingfilm in which at least one edge of the backing film is so treated so asto provide a shorter elastic side on the diaper, acting as though itcontains a separate elastic band. Thus, in accordance with the presentinvention there is provided a less cumbersome and a less expensivemanner of preparing a "stretch" diaper.

SUMMARY OF THE INVENTION

In accordance with the present invention there is provided a body memberconformable disposable article comprising

(a) a flexible, elastic and easily stretchable thermoplastic moistureimpermeable backing film and

(b) an absorbent layer superimposed thereon, at least one portion of atleast one edge of said backing film, at a position to be fitted around abody member of the wearer, having been folded upon itself and sealedtogether at the fold, so that when said backing film is laid flat saidone edge thereof is in stretched condition. The disposable articlepreferably includes a porous facing layer covering the opposite surfaceof the absorbent layer to that covered by the backing film.

The backing film preferably possesses

(1) an elastic recovery from 50% stretch of at least about 75%,

(2) a rubber modulus of not above about 2,000 pounds per square inch at50% elongation, and

(3) a Gurley stiffness at a thickness of 1 mil of not above about 1.

The topsheet is preferably elastic and easily stretchable. In fact, theelastic film used for the backing film may also be used for thetopsheet, in which event said topsheet is suitably shaped or perforatedto define a multiplicity of holes or openings through which a liquid maypass into the dressing to be absorbed by the pad. Since the topsheet inthis case is nonabsorbent, it also acts as a barrier which protects thewearer or user of the diaper, for instance, from direct contact with thewet pad. Other porous or perforated extensible and elastic topsheets mayalso be used. In this connection, various types of extensible orstretchable nonwoven fabrics are suitable. The topsheet may be made froman extensible nonwoven fabric which is also elastic such as disclosed inU.S. Pat. No. 3,485,706. A preferred form of this type of nonwovenfabric consists predominately of entangled polyester fibrous elements.

The backing film is most preferably formed from an elastomeric andthermoplastic film-forming composition which comprises an elastomericcomponent and 0-200 parts of a resin component per 100 parts by weightof the elastomeric component; the elastomeric component consistingessentially of linear or radial A-B-A block copolymers or mixtures ofthese linear or radial A-B-A copolymers with simple A-B blockcopolymers, the A-blocks being derived from styrene or styrene homologsand said B-blocks being derived from conjugated dienes or lower alkenes;the resin component consisting essentially of lower molecular weightresins adapted to associate principally with the thermoplastic A-blocksof the block copolymers.

The preferred disposable article of the present invention comprises anintegral disposable diaper conformable with a body member comprising

(a) a flexible, elastic and easily stretchable thermoplastic moistureimpermeable backing film having two longitudinal and two lateral edges,

(b) an absorbent layer superposed thereon and

(c) a moisture permeable topsheet joined to the backing film along theedges and forming an enclosure for the absorbent layer, at least oneportion of at least one longitudinal edge of the backing film, at aposition to be fitted around a body member of the wearer, such as theleg, having been folded upon itself and sealed together at the fold, sothat when the backing film is laid flat the longitudinal edge thereof isin stretched condition. In the case of a diaper, it is, of course,preferred that at least one portion of each of the two longitudinaledges of the backing film, at positions to be fitted around the two legsof the wearer, have been folded upon themselves and sealed together atthe fold so that when the backing film is laid flat, both of thelongitudinal edges are in stretched condition.

A preferred embodiment of the diaper of the present invention is one inwhich the backing film overlaps and extends beyond the topsheet alongeach longitudinal edge.

A further embodiment of the diaper of the present invention is providedwith the topsheet having two longitudinal edges overlaying thecorresponding longitudinal edges of the backing film, the topsheet beingformed with at least one slit at each longitudinal edge to enhancestretching in the area of the longitudinal edges along the lengththereof.

The present invention also comprises an article which includes a fabriclayer affixed to the backing film on the side thereof opposite to theside attached to the absorbent layer. This fabric layer provides greatersoftness to the touch than does the thermoplastic backing film. In theevent that the two longitudinal edges of the fabric layer should overlaythe corresponding longitudinal edges of the backing film, then thefabric layer is formed with at least one slit at each longitudinal edgeto enhance stretching in the area of the longitudinal edges of thefabric layer along the length thereof. More than one slit would bepreferred in this connection.

In an embodiment of the present invention in which the topsheet has atleast one lateral edge overlaying the corresponding lateral edge of thebacking film, the lateral edge of the topsheet is preferably formed withat least one slit (and more preferably two or more) to enhancestretching in the area of the lateral edge of the topsheet along thelength thereof.

The present invention is also directed to the process for preparing theabsorbent article discussed above. In preparing the absorbent article,the backing film is folded upon itself and sealed at least at oneportion of the folded edge of the backing film at the fold. Theabsorbent layer may be affixed to the backing film before or after theheat sealing step. In order to prepare an article containing only thebacking film and an absorbent layer, the latter may be affixed to thebacking film with a suitable adhesive or by heat sealing. When thedisposable article is intended to be used as a diaper, the absorbentlayer will normally be of considerably smaller area than the backingfilm, but when preparing articles such as gowns and bibs, the absorbentlayer may be of substantially the same area as the backing film.

When preparing a diaper which comprises a backing film, an absorbentlayer, and a moisture permeable topsheet, wherein the length of thelateral edges of the topsheet are less than those of the correspondinglateral edges of the backing film such that the backing film overlapsand extends beyond the topsheet along each longitudinal edge, the diapermay be prepared by sandwiching the absorbent layer between the backingfilm and the topsheet and joining the topsheet along its edges to thebacking film (preferably by heat sealing). Thereafter, at least oneportion of at least one longitudinal edge of the backing film is foldedupon itself and said one portion of the folded edge of the backing filmis sealed at the fold (preferably by heat sealing, although a suitableadhesive may be used). It is of course preferable, in the case of adiaper to fold at least one portion of each of the two longitudinaledges of the backing film upon themselves and to thereafter seal saidportions of the folded edges of the backing film at the folds. Althoughonly one folded and sealed portion (which will hereinafter be referredto as "pinched portion") is necessary at each longitudinal edge of thediaper, nevertheless it may be desirable to prepare two or more of suchpinched portions along each longitudinal edge in order to reduce thelength thereof and thus to increase the effective stretch. The pinchedportions may be spaced apart from one another or alternatively a portionof each longitudinal edge may be corrugated with a number of overlappingfolds and the corrugated portion thereafter sealed together.

The heat sealing step, per se, is carried out in a conventional manner.However, Applicant has found it expedient to place each corner of thefolded over edge of the backing film between the nips of a pair ofheated rollers in order to effect the heat sealing of such pinchedportions of the disposable article.

In the instance wherein the topsheet has substantially the same area asthe backing film (that is when the longitudinal edges of the topsheetoverlay the corresponding longitudinal edges of the backing film) it isdesirable to form the topsheet with at least one slit in eachlongitudinal edge thereof to enhance stretching in the area of thelongitudinal edges of the topsheet along the length thereof. In theabove instance, it is preferable to first prepare the sealed "pinchedportions" of the longitudinal edges of the backing film and to sandwichthe absorbent layer between the backing film and the topsheet;whereafter the topsheet is joined to the backing film along the edges ofthe topsheet (preferably by heat sealing in a conventional manner).

In an alternative embodiment, in the instance wherein the topsheet hassubstantially the same area as the backing film, at least one notch maybe formed in the topsheet in the area wherein the "pinched portion" ofthe longitudinal edge of the backing film is to be formed. In this casethe "pinching" may be carried out before or after the absorbent layer issandwiched between the backing film and the topsheet.

The backing film of the present invention must, of course, be elasticand easily stretchable as well as highly flexible. Furthermore, it isalso highly advantageous if the backing film is highly thermoplastic andeasily heat sealable. Any backing film having the aforementionedcharacteristics would be suitable for the present invention. However, itis preferred that the backing film should possess an elastic recoveryfrom 50% stretch of at least about 75%, preferably at least about 90%; a50% rubber modulus of not above about 2,000, preferably not above about1,000 pounds per square inch at 50% elongation and a Gurley stiffness ofnot above about 1 at a thickness of about 1 mil. This is a highlyflexible easily stretchable film which is elastic and tends to return toits original configuration when in a diaper and stretched around a babyfor example. However, since the film has a low modulus and stretcheseasily it will not grip the baby too tightly either during stretching orafter it is secured in position. The edges of the diaper having the"pinched portions" of the present invention convert the diaper into a"stretch" diaper, i.e., the kind of diaper having elastic bands, or theequivalent, which render the diaper conformable around body members suchas the legs.

As pointed out above, the backing film of the present invention ispreferably highly thermoplastic and easily heat sealable, i.e., it isadapted to form permanent heat seals to substrates such as paper andboxboard at relatively low heat sealing peak temperatures, generally notabove about 350° F., in less than 4 seconds of clamping time, asdescribed more fully hereinafter. It also preferably is capable of highelongation before breaking, i.e., it possesses an elongation to break ofat least about 300 percent, preferably at least about 400 percent.

The preferred film of this invention is formed from an elastomeric andthermoplastic film-forming composition which comprises an elastomericcomponent and 0-200 parts, preferably 85-200 parts of a resin componentper one hundred parts by weight of the elastomeric component. Theelastomeric component consists essentially of linear or radial A-B-Ablock copolymers or mixtures of these linear or radial A-B-A blockcopolymers with simple A-B block copolymers. In these block copolymersthe A-blocks are derived from styrene or styrene homologs and theB-blocks are derived from conjugated dienes or lower alkenes. The resincomponent consists essentially of low molecular weight resins,preferably having a number average molecular weight not above about3,000, and which are adapted to associate principally with thethermoplastic A-blocks of the said block copolymers.

In addition, the thermoplastic-elastomeric composition used forpreparing the backing film may be of a novel alloy such as that of anA-B-A block copolymer and a copolyester, e.g., an ester polymer of atleast two different ester units as more fully described in U.S. Pat. No.4,301,255.

The above backing film may be extruded hot from particulate, solid orliquid film-forming components, cast from a hot melt, formed by coatingfrom solution, or the like. It preferably is extruded from dryparticles. The film then is laminated with a layer of absorbent materialwhich may comprise paper, wood pulp or other absorbent material such assuperabsorbents in a suitable matrix and preferably is configured so asto be extensible, such as by creping. In one preferred form of theinvention, the backing film is heat sealed to the absorbent layer byusing the high sealing properties of the backing film itself. The heatseals may be formed only at the corners of the dressing or otherwisespaced from one another for increased flexibility. In disposablediapers, the side of the absorbent layer opposite to the backingnormally is covered with a highly porous facing sheet of paper ornonwoven fabric.

In another preferred form of the article of this invention, the backingfilm and the absorbent layer or pad are assembled in such a way thatportions of the backing film are extensible independently of theabsorbent layer in the direction of their interface. Thus, theseportions can be stretched without stretching the absorbent pad so thatthe pad need not be extensible. For instance, the backing film mayextend beyond the edges of the absorbent pad to form flaps on eitherside of the dressing which are extensible independently of the absorbentpad or that portion of the backing which is directly attached to thepad, or the absorbent pad may be attached to the backing over only alimited region disposed inwardly of corners of the pad to permit thoseportions of the backing film superimposed with marginal portions of thepad to be stretched or extended independently of those marginalportions, as disclosed in U.S. Pat. No. 3,981,306. Furthermore, indisposable diapers the shape of the backing film and the shape of theabsorbent pad, the relationship between the backing film and the pad,and the attachment or adherence between the film and the pad all may bevaried to provide different extensibility and conformabilitycharacteristics.

In still a different embodiment of the article of this invention theelastic and easily stretchable film material of the backing also may beused for the topsheet or facing film which covers the opposite surfaceof the absorbent layer or pad. The elastic topsheet is suitably shapedor perforated to define a multiplicity of holes or openings throughwhich liquid may pass into the dressing to be absorbed by the pad. Sincethe topsheet in this case is nonabsorbent, it also acts as a barrierwhich protects the wearer or user of a diaper, for instance, from directcontact with the wet pad. This form of the article of this invention isparticularly conformable since both the backing film and the topsheetare flexible, elastic and easily stretchable. Other porous or perforatedextensible and elastic topsheets also may be used in the article of thisinvention. As indicated hereinbefore, various types of extensible orstretchable nonwoven fabrics may be used as topsheets. In one preferredembodiment of a disposable diaper according to this invention thetopsheet is an extensible nonwoven fabric which also is elastic.

As indicated hereinbefore, the film-forming composition useful for thisinvention may comprise an elastomeric component and a resin component,and the elastomeric component may consist essentially of linear orradial A-B-A block copolymers or mixtures of these A-B-A blockcopolymers with simple A-B block copolymers. However, the proportion ofA-B block copolymers in the mixture of A-B-A and A-B block copolymersshould not exceed about 75% by weight and lower percentages normallywould be used.

The A-B-A block copolymers are of the type which consist of A-blocks(end blocks) derived, i.e., polymerized or copolymerized, from styreneor styrene homologs; and B-blocks (center blocks) derived fromconjugated dienes, such as isoprene or butadiene, or from lower alkenes,such as ethylene and butylene. Small proportions of other monomers alsomay enter into the block copolymers themselves. The individual A-blockshave a number average molecular weight of at least about 6,000,preferably in the range of about 8,000-30,000, and the A-blocksconstitute about 5-50 percent, preferably about 10-30 percent, by weightof the block copolymer. The number average molecular weight of theB-blocks for linear A-B-A block copolymers preferably is in the range ofabout 45,000-180,000 and that of the linear copolymer, itself,preferably is in the range of about 75,000-200,000. The number averagemolecular weight of the radial A-B-A copolymers preferably is in therange of about 125,000-400,000. The designation A-B-A includes what aresometimes called A-B-C block copolymers wherein the end blocks aredifferent from one another but both are derived from styrene or styrenehomologs. This applies both to linear and radial block copolymers. Theterm "linear block copolymer" (or copolymers) includes branched A-B-Acopolymers as well as unbranched A-B-A copolymers.

The radial A-B-A polymers useful in this invention are of the typedescribed in U.S. Pat. No. 3,281,383 and conform to the followinggeneral formula: (A-B)_(n) X, wherein A is a thermoplastic blockpolymerized from styrene or styrene homologs, B is an elastomeric blockderived from conjugated dienes or lower alkenes, as indicated above, Xis an organic or inorganic connecting molecule with a functionality of2-4 as described in U.S. Pat. No. 3,281,383 or possibly with a higherfunctionality as described in the article entitled "New Rubber is Backedby Stars" appearing on page 35 of the June 11, 1975 issue of ChemicalWeek. "n" then is a number corresponding to the functionality of X.

The A-B block copolymers useful for this invention are of the typedescribed in U.S. Pat. Nos. 3,519,585 and 3,787,531 and comprise A andB-blocks derived from the monomers described hereinbefore in connectionwith the A-B-A copolymers.

The elastomeric component of the film-forming composition useful forthis invention may include small amounts of other more conventionalelastomers but these should not exceed about 25 percent by weight of theelastomeric component. These other elastomers may include, highly brokendown natural rubbers and butadiene-styrene random copolymer rubbers,synthetic polyisoprene, chloroprene rubbers, nitrile rubbers, butylrubbers, and the like. Potentially elastomeric liquid polymers also maybe employed as additives but normally in lower proportions not aboveabout 10 percent by weight of the elastomeric component.

The resin component useful for the backing film of this invention, ifemployed, consists essentially of low molecular weight resins which areadapted to associate principally with, and are principally compatiblewith, the thermoplastic A-blocks of the said block copolymers. Theseinclude low molecular weight resins based on poly-alpha-methylstyrene,polystyrene, polyvinyl toluene and similar aromatic resins, as well ascopolymers thereof, coumarone indene and related cyclic compounds.Preferred resins for this purpose possess a number average molecularweight not above about 3,000 although higher molecular weight resins inthe low molecular weight range also may be employed. Small proportions,i.e., not above about 25 percent of the elastomeric component, ofvarious other resins, which (if tack is desired) may includeconventional tackifying resins such as hydrocarbon resins, rosin,hydrogenated rosin, rosin esters, polyterpene resins, and the like, alsomay be employed in the resin component of the film-forming composition.

The film-forming composition also may contain relatively smallproportions of various other materials such as antioxidants, heatstabilizers and ultraviolet absorbers, release agents, extenders,fillers and the like. Typical antioxidants are 2,5 ditertiary amylhydroquinone and ditertiary butyl cresol. Similarly, conventional heatstabilizers such as the zinc salts of alkyl dithiocarbamates may beused. Lecithin is one release material which has been found to beparticularly suitable in minor amounts in this type of extrudableparticulate mixture. However, waxes and various other release agents orslip agents also may be added in this manner.

Relatively small proportions, in the neighborhood of 25 parts by weightof the elastomeric component, of various extenders such as highermolecular weight polystyrenes, nonreactive phenol-formaldehyde resins,linear polyester resins, polyethylene, polypropylene, etc., also may beincluded in the film-forming composition. Similarly, the particulatemixture may include relatively small proportions, say 25 parts by weightof the elastomeric component, of fillers and pigments such as zincoxide, aluminum hydrate, clay calcium carbonate, titanium dioxide,carbon black and others. Many of these fillers and pigments also may beused in powdered form as parting agents to be mixed with thermoplasticelastomer particles to prevent these particles from agglomerating priorto blending with resin particles and other materials.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a view of the topsheet side of a rectangular diaper whileretained in a flat position. This view shows an absorbent pad sandwichedbetween an elastic thermoplastic moisture impermeable backing film and aporous topsheet.

FIG. 2 is a view of the backing film of FIG. 3 folded upon itself, inthe middle, a section of each of the two longitudinal edges of thebacking film having been sealed together at the fold.

FIG. 3 is a top view of the backing film shown in FIG. 2 after thelatter has been unfolded and placed in a flat position and showing the"pinched" sealed sections in each longitudinal edge of the backing film,whereby each of said longitudinal edges is in a stretched state.

FIG. 4 is a sectional view taken along 4--4 of FIG. 3.

FIG. 5 is a sectional view taken along 5--5 of FIG. 1.

FIG. 6 is a perspective view of the diaper of FIG. 3 after it has beenreleased from its flat position showing puckered portions of the backingfilm due to the release of the stretching of the "pinched" longitudinaledges.

FIG. 7 is a top view of the topsheet side of the diaper of FIG. 1,showing the manner in which slits formed in the upper lateral edge ofthe diaper, have opened up after the upper edge is stretched such as inthe instance when said upper edge is pulled tight around a baby's waist.

FIG. 8 is a perspective view of the diaper of FIG. 3 in itsconfiguration as applied to an infant.

DETAILED DESCRIPTION OF THE INVENTION

Referring first to FIG. 1 there is shown a flat view of an integraldisposable diaper 20 having a fluid permeable topsheet 21, an absorbentlayer 22 shown with dashed lines and a fluid impermeable backing film27, the absorbent layer 22 being sandwiched between said topsheet 21 andsaid backing film 27. The laminated structure of these three componentsis more clearly shown in FIG. 5. It will be noted that in FIG. 1 thetopsheet 21 completely overlays the backing film 27. Slits 23 and 25 areformed in the topsheet 21, so that when the diaper is stretched, theslits 21 and 25 enhance the ability of the edges of the topsheet 21 tostretch accordingly. In this connection, reference should be made toFIG. 7 which shows the diaper when it is stretched laterally at the topedge such as would be the case when a baby is diapered and the diaper ispulled tight around the baby's waist so that the slits 25 will tend toopen up and the backing film 27 may be seen through the openings.

In FIG. 3 there is shown a flat view of an integral disposable diaper 30having a fluid permeable topsheet 31, an absorbent layer 22 shown withdashed lines and a fluid impermeable backing film 32, the absorbentlayer 22 being sandwiched between said topsheet 31 and said backing film32. The laminated structure of these three components is more clearlyshown in FIG. 4. In said FIG. 4 it will be noted that the topsheet 31extends over a smaller area than the backing film 32 (i.e., the backingfilm 32 overlaps and extends beyond the topsheet 31 along eachlongitudinal edge 36). In view of said overlapping edge 36 in diaper 30of FIG. 3, it is not essential to provide any slits in the longitudinaledges of the topsheet 31 of the embodiment of FIG. 3 (such as the slits23 in the topsheet 26 of the embodiment of FIG. 1). However, slits 34are formed in the lateral edge of the diaper 30 as shown in FIG. 3, sothat when the latter is stretched at the top edge the slits 34 enhancethe ability of the topsheet 31 to stretch.

Turning to FIG. 2 it will be seen that the backing film 32 has beenfolded midway upon itself around the midline 35 and the corner portions37 have been sealed (preferably by means of heat, although an adhesivemay be used instead). The heat sealing is preferably carried out bypassing each corner portion 37 of the folded backing film 32, betweenthe nips of pairs of heated rollers at temperatures in the range between250° and 350° F. A further embodiment of the present invention comprisescorrugating the portions 37 of the folded backing film 32 before theheat sealing step is carried out.

It is desirable that the sealed "pinched portions" 37 be equal in lengthalong the longitudinal edges of the diaper so that the reduction inlength of said longitudinal edges should be of equal magnitude. Afterthe backing film 32 is opened up, and laid flat as shown in FIG. 3, thelongitudinal edges 36 of the diaper will be under stretch. If desired,backing film 32 could be folded, a further time, around a line remotefrom midline 35 and then sealed at the new fold. In this manner, two ormore "pinched portions" can be sealed and formed in each longitudinaledge of the diaper so as to proportionately increase the amount ofstretch therein.

The absorbent layer 22 and the topsheet 31 may be affixed, in aconventional manner, to the backing film 32 before or after thepreparation of the "pinched portions" 37 when preparing diaper 30 asshown in FIG. 3. When preparing diaper 20 as shown in FIG. 1, it is moreexpedient to first prepare the "pinched portions" in the longitudinaledges of the backing film 27 and thereafter to sandwich the absorbentlayer 22 between the backing film 27 and the topsheet 21 and joining thetopsheet 21, along its edges to the backing film using a suitableadhesive or by heat sealing.

As will be noted from FIG. 6, when the diaper of FIG. 3 is no longerheld flat, the stretch in the longitudinal edges will cause the diaperto be curved as in any normal "stretch" diaper and the backing film 32will become slightly puckered along the longitudinal edges.

FIG. 8 shows the diaper of FIG. 3 in its configuration as applied to aninfant whose trunk would occupy space "A" and the leg spaces "B".Conventional fastening tabs 41 may be employed to hold the diaper inplace around the trunk. Due to the stretch around the infant's waist,the slits 34 are shown to have been opened up. The longitudinal edges ofthe backing film 32 form a tight fit around the leg spaces "B".

U.S. Pat. No. 4,036,233 discloses a disposable diaper having a topsheetand a backsheet, one of which is stretchable, the other nonstretchableand wherein both extend beyond the edges of the absorbent material toprovide a waistband. The nonstretchable sheet is provided with openingsto permit stretching of the waistband. These openings have a somewhatsimilar effect to the slits 25 shown in FIG. 7 of the present invention.

The following examples of the backing films useful in absorbent articlesaccording to this invention are given only by way of illustration andare not intended to limit the scope of the invention in any way. Table Agives the film compositions for Examples I-III together with thephysical characteristics of the films. In the examples, all proportionsare expressed in parts per one hundred parts by weight of the totalelastomeric component unless otherwise indicated.

Film thickness is expressed in mils, or thousandths of an inch, tensilestrength is pounds per square inch to break the film as measured on anInstron tensile tester with an initial jaw separation of one inch at aspeed of twelve inches per minute, and elongation is the percentagewhich the film must be stretched in a given direction to break it, i.e.,stretched dimension at break minus normal dimension, over normaldimension in that direction, times a hundred. In all cases thedesignation "M.D." means "machine direction" lengthwise in the directionof processing and "C.D." means "cross direction."

Elastic recovery is percentage of immediate recovery in length afterbeing stretched fifty percent of original length and then released toallow free return. It is a function of the amount of stretch recoveredover the amount of stretch. The amount of stretch equals the length whenstretched minus the original length and the amount of stretch recoveredequals the length when stretched minus the length after recovery. Rubbermodulus is tensile stress in pounds per square inch of initial crosssection measured at one half inch extension per inch of length or 50percent elongation. This also is called 50 percent rubber modulus.

Gurley stiffness is measured as an opposite or inverse measure offlexibility with a standard Gurley stiffness tester using 1.0 by 1.5inch samples with 1/4 inch of sample in the jaw and 1/4 inch overlappingthe blade. The measured Gurley stiffness then is converted to stiffnessat a thickness of one mil by dividing the measured stiffness by the cubeof the measured thickness in mils. The coefficient of sliding frictionis measured by drawing the film samples horizontally over a chromeplated smooth metal panel with a 500 gram weight on top of the film.This is done in a TLMI adhesion tester at a pulling speed of 12 inchesper minute.

Heat sealability is measured by clamping each film sample in an opensandwich with a sheet of standard fiberboard test material between thejaws of an Erich International Corporation Bag Sealer at 42 p.s.i. airpressure. The fiberboard is Standard Reference Material 1810 specifiedin United States Department of Commerce Standard for Tape AdhesionTesting No. 16 (M:L-B-131E, Class 2). One of the jaws is heated and theother is unheated. The boxboard is placed in contact with the heated jawand the film in contact with the unheated jaw. Both jaws are cooled toambient temperature by air jets prior to clamping. When the testmaterial is in position between the jaws, the bottom jaw is heated by anelectric heater to seal the film to the boxboard by heat transferredthrough the board. The heating time period required to heat the lowerjaw to the minimum peak temperature necessary to permanently heat sealthe film of the boxboard, using a clamping period of 4 seconds, then ismeasured. The minimum peak permanent heat sealing temperaturecorresponding to the time recorded, then is obtained by reference to atime-temperature calibration curve for the instrument obtained bymeasuring temperatures at the bonding surface of the boxboard. Theminimum peak temperature referred to is that reached at the time theelectric heater is deenergized at the end of the heating time period.

                  TABLE A                                                         ______________________________________                                                           Examples                                                   Ingredients & Characteristics                                                                      I           II      III                                  ______________________________________                                        Kraton 1107 S-I-S Linear Copolymer                                                                 100                 100                                  Solprene 420 S-I-S Radial Copolymer                                                                            100                                          Amoco 18-210 Resin                       150                                  Amoco 18-290 Resin   100         100                                          Zinc Dibutyl Dithiocarbamate                                                                       1           2       1                                    (Antioxidant)                                                                 2,5 Ditertiary Amyl Hydroquinone                                                                   1/2         1/2     1/2                                  (Antioxidant)                                                                 Titanium Dioxide Pigment                                                                           5                                                        Thickness, (Mils)    3.6         4.2     3.0                                  Rubber modulus @ 50% Elongation,                                                                   800         115     475                                  lbs./in..sup.2                                                                Elongation (M.D.),%  530         1200    2100                                 Elongation (C.D.),%  750         1140    1260                                 Tensile Strength (M.D.), lbs./in..sup.2                                                            1220        600     900                                  Tensile Strength (C.D.), lbs./in..sup.2                                                            1050        570     970                                  Gurley Stiffness, mg./in..sup.2 / mil                                                              0.38        0.42    0.05                                 Heat Sealing Temperature, °F.                                                               250         240     250                                  Friction Coefficient (Dynamic)                                                                     2.58        2.60    2.23                                 % Elastic Recovery After 50%                                                                       98          95      95                                   Elongation                                                                    ______________________________________                                    

It will be seen that the films of all of the above examples are highlyelastic, i.e., possess an elastic recovery after 50 percent elongationof well above about 90 percent. Furthermore, all the films possess a lowrubber modulus, in these examples, not above about 1,000 lbs./in.² at 50percent elongation.

The films of the examples are not particularly oriented as evidencedfrom the tensile strength readings in the machine and cross-directionsand generally possess a high elongation, i.e., at least about 500percent in both directions.

The films are highly flexible, exhibiting Gurley stiffness readings aslow as 0.05 mg./in.² /mil and no higher than 0.42 mg./in.² /mil. Theyalso are not slippery, i.e., they possess a dynamic coefficient offriction well above 0.5, more specifically between 2 and 3. The maximumpermanent heat sealing temperature determined as described hereinbeforeis about 250° F., well below 350° F.

In the foregoing examples Kraton 1107 copolymer is a thermoplasticelastomeric A-B-A (styrene-isoprene-styrene) block copolymer offered bythe Shell Chemical Company, wherein the styrene content (that of theA-blocks) is about 12-15 percent, closer to 15 percent by weight of theblock copolymer, and the polymer possesses a solution viscosity of about2,000 centipoises at 25 percent solids in toluene at room temperature(using a Brookfield Viscometer with a No. 4 spindle at 60 r.p.m.), and anumber average molecular weight of about 110,000-125,000. Solprene 420copolymer is a radial styrene-isoprene-styrene block copolymer of thetype described hereinbefore which has a number average molecular weightof 240,000 and a styrene content of about 15 percent.

Amco 18-210 and 18-290 resins are solid polyalphamethyl styrenes offeredby Amoco Chemical Co., with softening points of about 210° F. (99° C.)and 290° F. (143° C.) respectively.

Although the present invention has been described in detail with respectto diapers where there is a special need, it is obvious that it may beadapted to any article of similar nature in which conformability isdesired, particularly conformability around a body member such as neck,wrist, ankle, waist, etc. Thus it is adaptable to be employed withdisposable gowns, athletic tape, bibs, surgical stockinettes, bandagesand other health care products and industrial products.

In contrast to diapers and incontinence pads, other articles maycomprise a backing film and an absorbent sheet. A gown or other articlemay be made partly of a nonabsorbent moisture impermeable materialsimilar to a backing film of a diaper. These articles may be madeselectively conformable according to the method of the present inventionby forming a sealed "pinched" portion in the longitudinal edges thereofat the desired positions. In articles other than diapers andincontinence pads, the source of moisture is generally external so thata topsheet is not necessary to protect the skin from the liquid filledabsorbent pad as is necessary in a diaper.

Having now described the diaper in specific detail and exemplified themanner in which it may be carried into practice it will be readilyapparent to those skilled in the art that innumerable variations,applications, modifications and extensions of the basic principlesinvolved may be made without departing from its spirit or scope.

I claim:
 1. A process for preparing a body member conformable disposablearticle comprising: p1 (a) an electric thermoplastic moistureimpermeable backing film, and(b) an absorbent layer superposed thereon,at least one portion of at least one edge of said backing film, at aposition to be fitted around a body member of the wearer, having beenfolded upon itself and sealed together at the fold, so that when saidbacking film is laid flat said one edge thereof is in stretchedcondition; which process comprises providing an elastic thermoplasticmoisture impermeable backing film, folding at least one portion of atleast one edge of said backing film upon itself around a fold linerunning transversely of said one edge and forming at least one pinchedportion at the fold by sealed a portion of the folded edge of saidbacking film together at the fold, providing an absorbent layer, andaffixing the absorbent layer to the backing film.
 2. A process accordingto claim 1, in which the absorbent layer is affixed to the backing filmbefore the step of sealing the portion of the folded edge thereof.
 3. Aprocess according to claim 1, in which the absorbent layer is affixed tothe backing film after the step of sealing the portion of the foldededge thereof.
 4. A process according to claim 1, wherein the backingfilm prossesses:1. an electric recovery from 50 percent stretch of atleast about 75 percent.
 2. a rubber modulus of not about 2,000 poundsper square inch at 50 percent elongation, and
 3. a Gurley stiffness at athickness of 1 mil of not above about one.
 5. A process for preparing anintegral disposable diaper conformable with a body member comprising:(a)an elastic thermoplastic moisture impermeable backing film having twolongitudinal and two lateral edges, (b) an absorbent layer superposedthereon, and (c) a moisture permeable topsheet joined to said backingfilm along the edges of the topsheet and forming an enclosure for saidabsorbent layer, at least one portion of at least one longitudinal edgeof said backing film, at a position to be fitted around a body member ofthe wearer, having been folded upon itself and heat sealed together atthe fold so that when said backing film is laid flat, said onelongitudinal edge thereof is in stretched condition; which processcomprises providing an elastic thermoplastic moisture impermeablebacking film having two longitudinal and two lateral edges, providing anabsorbent layer, providing a moisture permeable topsheet having twolongitudinal and two lateral edges, the lengths of the lateral edges ofthe topsheet being less than those of the corresponding lateral edges ofthe backing film, sandwiching the absorbent layer between the backingfilm and the topsheet whereby the backing film overlaps and extendsbeyond the topsheet along each longitudinal edge, joining the topsheetalong its edges to the backing film, folding at least one portion of atleast one longitudinal edge of said backing film upon itself around afold line running transversely of said longitudinal edge and forming atleast one pinched portion at the fold by heat sealing a portion of thefolded edge of said backing film together at the fold,
 6. A process forpreparing an integral disposable diaper conformable with a body membercomprising:(a) an elastic thermoplastic moisture impermeable backingfilm having two longitudinal and two lateral edges, (b) an absorbentlayer superposed thereon, and (c) a moisture permeable topsheet joinedto said backing film along the edges of the topsheet and forming anenclosure for said absorbent layer, at least one portion of at least onelongitudinal edge of said backing film, at a position to be fittedaround a body member of the wearer, having been folded upon itself andheat sealed together at the fold so that when said backing film is laidflat, said one longitudinal edge thereof is in stretched condition, saidtopsheet having two longitudinal edges overlaying the correspondinglongitudinal edges of said backing film, said topsheet being formed withat least one slit at each longitudinal edge to enhance stretching in thearea of said longitudinal edges of said topsheet along the lengththereof; which process comprises providing an elastic thermoplasticmoisture impermeable backing film having two longitudinal and twolateral edges, providing an absorbent layer, providing a moisturepermeable topsheet having two longitudinal and two lateral edges,forming at least one slit at each longitudinal edge of said topsheet,folding at least one portion of each of said two longitudinal edges ofsaid backing film upon themselves around fold lines running transverselyof said longitudinal edges and forming at least one pinched portion ateach fold by heat sealing a portion of each folded edge of said backingfilm together at the folds, and thereafter, sandwiching the absorbentlayer between the backing film and the topsheet and joining the topsheetalong its edges to the backing film so that the two longitudinal edgesof said topsheet overlay the corresponding longitudinal edges of saidbacking film.
 7. A process according to claim 5, wherein the topsheetcomprises a nonwoven fabric.
 8. A process according to claim 1, whichcomprises heat sealing the portion of the folded edge.
 9. A processaccording to claim 1, which comprises sealing the portion of the foldededge with an adhesive.